Barnstead — June 28, 2004 — A global positioning unit. A special permit to apply chemicals. A dive team to hand-pluck weeds at the depths of the lake, $86,000 and a group of scientists at the University of New Hampshire for research.

Officials think they may have found the formula to eradicate milfoil – if all goes as planned. On Friday, Lower Suncook Lake became the guinea pig for a host of experiments designed to eradicate the insidious underwater plant that has invaded 54 of the state’s 900 lakes and ponds since it arrived 40 years ago.

A Massachusetts company spent the day applying a chemical called 2,4-D to the milfoil, which had been precisely located by a GPS unit and scuba divers. Whatever survives the chemicals will be hand-pulled by divers for the rest of the summer. Meanwhile, three nearby drinking water wells will be monitored in hopes of dispelling ideas that the chemical migrates into groundwater. And UNH scientists are looking for ways to decrease the potency of the chemical, in case a future project contaminates a shallow well.

The state kicked in almost $61,000 toward the project, while the town paid $10,000. The balance came from divers, members of the Suncook Lake Association, who donated their time and equipment.

Variable milfoil grows up to 20 feet tall – or an inch a day – without treatment. The problem is compounded by the fish, which eat the native plants, making room for more milfoil. Eventually, native plants are pushed out by milfoil and fish die without food, leaving dirty water with milfoil so tall no one can swim or boat.

Lower Suncook Lake is critical in the battle against milfoil because it’s in the middle of the Suncook River watershed; the lakes to the south have had less trouble with milfoil than those to the north. But the milfoil could scatter downstream and infest other lakes, riding Lower Suncook Lake’s current.

Of the 216 acres the lake spans, 140 will be treated with the chemical, which state officials say won’t harm other plants or fish. It’s been used in New Hampshire water bodies since 1978, but the milfoil typically grows back within two or three years, officials said.

But this time is different. The maps plotting the milfoil were given to the company applying the chemicals. The company uses its own GPS unit to follow the course and precisely apply the chemicals. In a few weeks, divers will begin scouring the bottom of the lake to hand-pull any surviving milfoil. Then, lake association members will comb through the water with nets, picking up any milfoil fragments that could turn into new plants.

If every fragment of every plant is removed, milfoil might be history. “It’s possible,” said Jody Connor, state limnology director. “It’s also optimistic, but I’d like to see it happen.”

This is not the first time that the lake association has attempted a frontal assault on milfoil. The plant appeared in Lower Suncook Lake in 1995. Since then, different chemicals and hand-pulling have been attempted with little effect – but not simultaneously and never to this extent, officials said.

The wells, located at the southern end of the lake and chosen for their close proximity to the water, will be monitored by Environmental Services for a minimum of 30 days. It’s more of a precaution because New England states have never done so before, Connor said, even though other states have.

Officials say no one should swim in the water until Friday. Residents and others should also avoid drinking it, using it for irrigation or misting it with chemical sprays for landscaping for at least 30 days, or until further notice.